Abacus



I. E. BIRDSALL Nov. 21, 1950 ABACUS 2 Sheets-Sheet 1 Filed Feb. 5, 1948I N V EN TOR. gab/533572 6472 WW Patented Nov. 21, 1950 UNI-TED STATESPATENT oer-ice ABACUS Ida Birasau, Manasquan, N. .J." ApplicationFebruary 5, 1948, Serial No. 6,399

1 Glaiim (cites- 3s) I My invention relates t'oa modernized and improvedabacus',-,and' it is an-object of the same to provide an abacus thatshallpreserve allthe-advantages of speedy and accurate calculation foundin the oldand well-known-type of abacus while also-havin improvementstending'toward facility of use, economy of construction and readymutability for use under various conditions.

Referring to the accompanying drawings, which are made apart ofthisapplication andin which similar reference characters indicate. simi-'-lar parts:

Figs.- l, 2 and 3 are plan views of threeunits; one:ormore of whichmaybe'used in combina tion for making; calculations,

Fig; 4 is 2.:pBI'S1JBCtlV6 of -an element used with the-devicesshown-in. Figs.- 1, 2; 3:and 6,

Fig. 5 isa perspective .ofanotherelement that is used in making.;calculations;

Fig. 6 is'azperspective of-a'unit; illustrating the manner of operation,

Fig. 7 is a' plan of a'modified form of the invention,

Fig. 8, a-perspectiveof a part'" showninFig; 7, and

Fig. 9, a detail or parts 'shown in-Fig. '7.

In thedrawings, reierencecharacters H]; H and [2 indicate generallythree units of the'de vice-of my invention, which units areprefer-ablyformed as separate blocks that can be placedin close juxtaposition" sideby side,- but which can be formed as upstanding pro-jectionson a basethat can be integralwiththeblocks or aflixed thereto in any desiredmanner or for some uses the blocks will-be provided-with means fortemporarily attaching them removablyto any suit able base forholding'the'm in desired relationship. Preferably the units are eachofdifferent color from the others of a set.

Eachof the blocks-isshown as having slots or saw cuts 3 at intervals,the cuts-preferably numbering nine, so as to divide the upper surface ofa unit into ten similar parallelograms. At a suitable point on each ofsaid faces a hole [5 is provided, preferably at the center of the face,for receiving the lower endof a pin l6, such pins being provided innumber equal'tothe number of holes or substantiallyso, and-being made ofwood or other conveniently available material. Preferably the pins foreach block of a set are of'different color.

For insertion in the slots 1 @I provide strips of stiff materialwhichshou-ld be' smooth andihard and so proportioned as to-fit' easilyin'the slots and be readily removable therefrom. It" is desirable thatthe strips bemade-of so-called plastic materialthat is relatively freefrom any tendency tobreak or split and which can be washed withoutdamagethereto: Usually there willbe-more than one strip for each block,and they may be is merely illustrative, as will be obvious.

of difier'ent colors so that the strips and the pins may be of adifferent color from the block; for contrast. Obviously also the block,the pins, and the strips therefor may each be of different color,orall'of the same color, according to the conditions of use or becauseof personal preference or for any other reasons.

A'numeral is located-adjacent each hole IS, the numerals on the firstblock at the right being of the order of units, those on the next blockto the leftbeing' of the order of tens, those in the third of hundreds,and so on as far as may be desired.-

In the use of the'device of my invention three blocks may belocated nearone another as shown in Figs. 1, 2 and 3'and pins set up in the holesthereof as indicated in dotted lines-for one of the holes in Fig. 6. Forpurposes of computation strips H will be inserted in appropriate slots.

- For example if the numberfi'l is to be added to the number 211, theoperator may set a strip in the groove below the space marked at in themiddle column and another below the space marked 1 in the units column;then insert three strips respectively in the slotonespace below theoccupied one in the first column at the right in the next slotbelow theoccupied one in the middle column, and'a third. in the slot below thenumber 200 in the left-hand column. The order described may obviously bevaried. Then the result may be read at once as 278 by reading across theboard just above the strips; In the case-Oisubtraction the operationsare the reverse of those just described. The pins could be omitted,- butare of advantage as-afiording visual means-to assist in speedy andproper placement of the slips ii, and also they may be relied on forcomputation by unskilled persons, the blind, and under specialconditions. as where the light is dim or wanting.

Where the sum of numbers in a column exceeds ten the operation known'ascarrying is involved, and here the strip that'wouldbe inserted in a slotis carried over' to the next column. If, for instance, the sum of 67andl24 is required, the strips for one number are first set up, as'below60 in the middle column and below i in the units column. Then-thesettingup of the next number proceeds-from the. units column onward by firstattempting to insert the next strip four spaces below the slot numbered1; which, of course, cannot be done as the sum exceeds 10 by one. Sothestrip is set up in the middle column one space below the-.one alreadyin. that column or at-zthe seventh'position. Now another strip isinserted two spaces lower down "in the middle col urn-n, or at'the.ninth place. Then a strip is set into: the firstspace in the hundredscolumn and the. result again can be read by reading the numerals. abovethe lowermostlslots the resp'em tive. columns, 1. er, 19'1'.The'sequence-described For subtraction the reverse operation ipracticed. The highest sum that can be computed on the blocks, as shown,is 1110.

In the teaching of the operations of addin and subtracting, whichinvolve carrying in the one case and "borrowing in the other, a usefulexpedient is disclosed in Fig. '7. Here there are shown three blocks l8,l8 and 28 which may have the same construction as above described or maybe different within the limits of my invention, and the number of whichmay vary, as above explained. In this instance the blocks are fixedlymounted upon a base 2| or may be made integral therewith or removablyafixed thereto, as preferred.

Another block 22 (Fig. 8) which I call an insertion block, is formed asa separate member and may be placed between any pair of blocks on thebase 2|, according to the columns where computations are being made. Theblock 22 has nine cross slots 23 and ten holes 24, as in the case of theother blocks, and the base may be formed with some means coasting withthe block 22 for holding its slots in line with those of the fixedblocks, if desired, e. g., a slight. depression may be formed betweenthe pairs of fixed blocks into which the bottom portion of the removableinsertion block may fit to hold it against accidental movement, or itmay be a duplicate of the other blocks except for the omission of anynumerals adjacent the holes 24.

In the use of the modified form of the invention for addition theinsertion block is placed between the appropriate fixed blocks,dependent on whether units, tens, hundreds, etc. are being added. If twonumbers, as 6 and 8, are to be added in the column at the right of theinsertion block six pegs can first be placed in the holes of that row,then eight more pegs being attempted to be added would fill theremaining holes with an overflow of four pegs, which overflow pegs wouldthen be placed in the insertion block, thus forming a group of fourteenpegs. Now these fourteen unitary pegs are to be changed into one ten andfour digits and the insertion block removed. As a result, the childrencome to understand that six plus eight amounts to fourteen and thatfourteen can be changed into one ten and four units for convenience, theone ten being placed in tens row below the tens already there. that thenumbers to be added are 26 and 23, the operation may proceed just asabove outlined except that two tens are already in the tens column andthe placing of the third ten must be followed by placing the other twotens of the number 28 below those now in the second column, when thetotal of 54 can readily be read from the abacus, the insertion blockbeing removed or not as preferred.

Supposing that 28 is to be subtracted from 46, 3

the insertion block. Now the units block plus the insertion blockcontain sixteen ones, from which he can readily remove eight, leavingeight ones, all of which he will place in the ones column, and theinsertion block removed.

This is the first step, and as a second step the child will remove twopegs from the tens row, i. e., the two tens showing the number 28*, andthus leaves one peg standing in the tens row, therefore the answerstands as 18.

Supposin It will be understood that after the pupil becomes expert inthe use of the abacus with the insertion block he will ordinarily tendto dispense with the same, since the operations of carrying andborrowing become easy and the insertion block is no longer needed.

As an aid in teaching money values I may provide ten pegs 25 for eachcolumn, with flat heads 26, 21, 28, etc., as may be needed, the heads ofthe ten pegs of each set being provided respectively with numerals;to-wit, all pegs for the right-hand column to bear the numeral 1; allpegs for the second fixed columns to bear numeral 10; all pegs for thethird fixed column (counting from the right) to bear numeral 100 and soon.

Now to demonstrate that ten units equal one ten, there will be set up inthe right-hand column ten pegs bearing numeral 1 on their heads, orotherwise appearing on said pegs. As in changing money, i. e. changingten pennies to one dime, these ten pegs may be removed from the boardand a single 10 peg set up at the top of the second fixed column, wherethe numeral below it indicates the value.

In the first column the value of four 1s in the first four holes isindicated at the lowermost occupied hole. In like manner the firstcolumn may be filled four times, for example. Then after each fillingthe ten ls are removed and a 10 added to the second fixed column and,after four such additions the numeral 40 below the lowest occupied holeindie-ates the total, showing that four 10's equal 40, five 10s equal50, etc.

In like manner it'may be shown that ten 10s equal 100, four times ten10s equal 400, ten 100s equal 1,000, etc.

It will be obvious to those skilled in the art that many variations maybe made in the devices herein disclosed, all without departing from thespirit of the invention; and, therefore, I do not limit myself to whatis shown in the drawings and described in the specification, but only asindicated in the appended claim.

Having fully thus described my invention what I claim is:

A calculating device comprising a base, parallel elongated elementsfixedly located on said base, said elements having transverse slotsdividing the surface of each element into a plurality of fields eachhaving a hole adjacent one of said slots, pegs adapted to fit in saidholes, slips of sheet material adapted to fit in said slots, and aremovable insertible block proportioned to fit between two of saidparallel elements, said insertion block having a num er of slots andholes spaced eo uallv with the slots and holes of the adjacent parallelelements.

IDA E. BIRDSALL.

REFERENCES crrnn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 37,825 Reifelt Mar. 3, 1863227,159 Foote May 4, 1880 651,892 Schneider June 19, 1900 1,400,887Liebman Dec. 20, 1921 1,605,697 Birdsall Nov. 2, 1926 FOREIGN PATENTSNumber Country Date 11,804. Great Britain 1894

